The reason is simple, and it isn’t hedged: this tissue must be removed to help your wound heal.
Must. Not “may help,” not “is often done.”
Dead tissue also creates a practical problem. When a pressure sore is covered in dead skin that is yellow, tan, green, or brown, the dead skin makes it hard to tell how deep the sore is, and this type of sore is unstageable. A wound nobody can measure is a wound nobody can track.
It’s worth knowing ahead of time what’s underneath once it’s gone, because it startles people. After a debridement the wound may seem bigger and deeper, and the area will be red or pink in color and look like fresh meat. A foot ulcer should be red or pink afterward. Wounds that are pale, purple, or black are less likely to heal.
There are several methods, and the choice is a clinical one: surgical debridement with a scalpel, scissors or other sharp tools; a whirlpool bath; a syringe used to wash away dead tissue; wet-to-dry dressings, where a wet dressing is applied, allowed to dry, and pulled off along with the dead tissue; and enzymes applied to the wound to dissolve dead tissue.
One rule applies to all of them. You should never try to do this yourself. A provider, such as a podiatrist, will need to do this to make sure the debridement is done correctly and does not make the injury worse.